Moving the ACT sensor can require a remap, so definately not an ideal solution to try and get lower numbers.

The temperature correction tables that have been mapped for the ACT calibrated as it is currently in its present location would not be correct for it moved somewhere else which will give a different reading for what is in reality still the same temperature of charge actually entering the head.

With regards to the manifold, they are well proven at far past the flow rate you require for the sort of BHP you are quoting there, but as always with any manifold you can never have too much data so EGT senders in each cylinder would be a cheap bit of worthwhile insurance IMHO.